Reference table
Hazen-Williams C Values for Fire Sprinkler Pipe
Lookup common Hazen-Williams roughness coefficients for steel, copper, CPVC, cast iron, and dry-system sprinkler pipe materials.
Hazen-Williams C values pipe6 rows2 linked calculators
Rows
6
Reference values
Columns
2
Lookup fields
Linked tools
2
Calculators using this data
Page role
Use this page for a defined task before moving to the next project record.
- Audience
- Engineers, designers, reviewers, and technicians selecting calculator input values.
- Job
- Use this table when a sprinkler hydraulic check needs a C value tied to pipe material, condition, and wet or dry system context.
- Evidence
- Match pipe material and system condition before selecting the C value. Use old steel or dry-system assumptions only when the project basis supports the more conservative roughness value.
- Output
- Selected Common C Values row carried into 2 calculator workflows.
- Next
- Choose the matching row, review selection checks, then open the calculator or worksheet that consumes the value.
Source governance
Record how this table is used before carrying a value into a calculator, worksheet, or authority workflow.
| Governance item | Record | Use boundary |
|---|---|---|
| Source class | Engineering lookup table | Use the table as a controlled reference input, not as an adoption or approval database. |
| Last review basis | Static registry review | Re-check adopted standards, manufacturer data, and project criteria before final use. |
| Known limit | Manufacturer data, adopted edition, and project specifications can supersede a generic reference row. | Escalate unresolved code, listing, or jurisdiction questions to the project record. |
| Downstream record | Hazen-Williams Sprinkler Friction Loss Calculator, Sprinkler System Demand Calculator, NFPA 13 Hydraulic Design Worksheet | Keep selected rows with the worksheet, calculation package, or authority record. |
Reference table structure
Use these fields to filter the table, select a value, and retain the basis with the calculation record.
Rows
6
Filter fields
Pipe Material
Value columns
C Value
Related pages
3
| Table area | Values | Engineering use |
|---|---|---|
| Query examples | Pipe Material = Steel (new); Pipe Material = Steel (old or galvanized); Pipe Material = Copper | Use these values as table filters before carrying a row into a calculator. |
| Related calculators | Hazen-Williams Sprinkler Friction Loss Calculator, Sprinkler System Demand Calculator | Selected rows become calculation inputs or reasonableness checks for the linked tools. |
| Related worksheets | NFPA 13 Hydraulic Design Worksheet | Worksheet records preserve the selected value with the project assumption trail. |
Reference table use
Use the table as controlled input data: select the row, verify the condition, and carry the value to the related calculator.
Usage context
- 1Use this table when a sprinkler hydraulic check needs a C value tied to pipe material, condition, and wet or dry system context.
- 2Carry the selected C value into Hazen-Williams friction loss only after confirming it describes the same pipe segment as the flow and diameter.
- 3Keep the row with the hydraulic worksheet when old steel, dry pipe, or project specifications control the roughness assumption.
Selection rules
- 1Match pipe material and system condition before selecting the C value.
- 2Use old steel or dry-system assumptions only when the project basis supports the more conservative roughness value.
- 3Do not reuse a C value across different pipe materials or condition assumptions without a recorded reason.
Review checks
- 1Selected C value matches pipe material, condition, and system type for the reviewed segment.
- 2Flow, internal diameter, length, and C value all describe the same hydraulic path.
- 3The downstream Hazen-Williams result is retained with the C value source and any conservative assumption.
| Reference field | How to use it | Related tools |
|---|---|---|
| Pipe Material | Use this field to identify the matching project condition. | Hazen-Williams Sprinkler Friction Loss Calculator, Sprinkler System Demand Calculator, NFPA 13 Hydraulic Design Worksheet |
| C Value | Carry this value into the downstream calculator with the displayed units and label. | Hazen-Williams Sprinkler Friction Loss Calculator, Sprinkler System Demand Calculator, NFPA 13 Hydraulic Design Worksheet |
Selection examples
Use these examples to choose a row deliberately before carrying the value into a calculator or worksheet.
| Scenario | Row choice | Reason | Downstream use |
|---|---|---|---|
| New wet-pipe sprinkler main using black steel pipe. | Use the steel wet-pipe row when it matches the project specification and pipe condition. | The C value should describe the same material and service condition as the hydraulic segment. | Carry the selected C value into the Hazen-Williams calculator with the segment flow, internal diameter, and equivalent length. |
| Existing dry system branch line with unknown internal condition. | Use the dry or older steel assumption only when the project basis supports the conservative roughness value. | Dry systems and older steel can have rougher interior conditions than new wet-pipe steel. | Retain the conservative row with the hydraulic worksheet and flag the assumption for engineering review. |
| CPVC branch piping downstream of steel feed main. | Select separate rows for CPVC and steel segments instead of applying one C value to the full path. | Different materials in one hydraulic path need segment-by-segment friction-loss treatment. | Calculate each segment with its own C value, then combine losses in the hydraulic worksheet. |
Selecting a C value for a mixed sprinkler path
Assumptions
- 1A preliminary NFPA 13 hydraulic screen includes 180 ft of new Schedule 10 black steel main and 60 ft of CPVC branch pipe.
- 2The steel main and CPVC branch are different hydraulic segments, so each segment keeps its own material and C value.
- 3The calculation is a screening workpaper, not a sealed hydraulic calculation.
Steps
- 1Select the steel wet-pipe row for the black steel main if it matches the project pipe condition.
- 2Select the CPVC row for the branch segment if CPVC is listed and permitted for the project condition.
- 3Run Hazen-Williams separately for the steel segment and the CPVC segment using each segment's flow, internal diameter, length, and C value.
- 4Add the segment losses in the hydraulic worksheet and retain both selected rows as the roughness basis.
Result
The useful output is not one blended C value. The project record should show two selected reference rows and two friction-loss calculations before the total path loss is used downstream.
Misuse warnings
- 1Do not use one C value across mixed steel, copper, CPVC, and old dry-pipe segments unless the calculation intentionally models a conservative single-segment screen.
- 2Do not choose a higher C value only to reduce friction loss; the value must follow the pipe material, condition, and project basis.
- 3Do not treat the table as proof that an old or obstructed pipe is hydraulically equivalent to new pipe without inspection, project criteria, or engineering judgment.
Common C Values
| Pipe Material | C Value |
|---|---|
| Steel (new) | 140 |
| Steel (old or galvanized) | 100 |
| Copper | 150 |
| CPVC | 150 |
| Black steel dry system | 100 |
| Cast iron | 100 |
Engineering disclaimer
NFPA in USA provides engineering workpapers, calculation checks, and reference tables for project screening and coordination. Final design decisions, code interpretations, submittals, and acceptance records must be completed by qualified professionals and verified against the adopted code, project criteria, listings, and Authority Having Jurisdiction requirements. This site does not issue signed or sealed engineering documents.Tools and workflows that use this table
FAQ
How should this C value table be used?+
Use it as an engineering reference source for selecting values, checking assumptions, and documenting the basis carried into a calculator or worksheet.
Can this table replace the sealed project record?+
No. Values still need to be checked against the adopted standard, manufacturer data, project specifications, and Authority Having Jurisdiction requirements before they are used in final documents.